Method

To make the mornay sauce, chop the cauliflower, stem and all, into small, even pieces. Place the cauliflower in a saucepan, cover with the milk and season with a pinch of salt, pepper and nutmeg. Bring to the boil over medium heat and simmer for 20–30 minutes until the cauliflower is tender and the milk has reduced by half. Remove from the heat and, using a slotted spoon, transfer the cauliflower pieces to a blender, reserving ½ cup for later.

Add 3 tablespoons of the hot milk and blend until very smooth. If too thick, add more hot milk to achieve a double cream consistency. Add the egg yolks, grated cheese and mustard and blitz to combine. Season to taste.
Preheat the oven to 200°C. Grease a 2 litre baking dish.

Gently combine the tuna (including the springwater), risoni, reserved cauliflower pieces and a pinch of salt and pepper in the prepared dish. Spread out evenly, then pour on the ‘mornay sauce’.

For the crunchy rosemary crust, combine the breadcrumbs, olive oil, cheese and rosemary leaves in a bowl and rub between your fingers until the breadcrumbs and rosemary are lightly coated in the oil (this helps the crust brown evenly and releases the wonderful aroma of the rosemary).

Scatter the rosemary crust over the tuna mornay and bake for 25–30 minutes until golden and bubbling. Cool for 4–5 minutes before serving.